Method of removing mems devices from a handle substrate

Abstract

A method of removing MEMS devices ( 2 ) from a handle substrate ( 1 ), where the MEMS devices are individually bonded to it via a thermal release adhesive ( 3 ) that reduces its adhesion when heated above a threshold temperature. The method heats the MEMS devices ( 2 ) individually with a heat source ( 10 ) to conductively heat the thermal release adhesive ( 11 ) above the threshold temperature. With the adhesive ( 11 ) directly in contact with the back side ( 5 ) of the MEMS device ( 2 ) no longer bonding it to the glass handle ( 1 ), the devices ( 2 ) can be individually removed by a die picker ( 6 ). This method quickly heats the adhesive to release each die in about 1 second. This is comparable to UV release adhesive and does not require a prior 30 minute drying bake. Furthermore, heating the die by conduction, will in turn conductively heat the adhesives that only that adhesive which is closely localized to the die is released. The adhesive that bonds the adjacent dies to the glass handle remains unaffected.

1 . A method of removing MEMS devices from a handle substrate, the method comprising the steps of:
 providing the handle substrate with the MEMS devices individually bonded to it via a thermal release adhesive that reduces its adhesion to the MEMS device when heated above a threshold temperature;   applying a heat source to at least part of one surface of each of the MEMS devices to heat the MEMS device above the threshold temperature; and,   individually removing the MEMS devices from the handle substrate.   
     
     
         2 . A method according to  claim 1  wherein the heat source is a laser. 
     
     
         3 . A method according to  claim 2  wherein the MEMS devices are removed from the handle substrate with a die picker that has an elongate arm with a free end configured to engage one of the MEMS devices, and the laser directs a beam through the die picker to heat the MEMS device prior to it removal. 
     
     
         4 . A method according to  claim 1  wherein the heat source is a heated surface configured for contact with the at least part of one surface of the MEMS device. 
     
     
         5 . A method according to  claim 4  wherein the heated surface is on a die picker used to lift the MEMS devices from the handle substrate after releasing the thermal adhesive. 
     
     
         6 . A method according to  claim 5  wherein the die picker has a resistive heater for generating heat, the resistive heater being controlled to keep heating rates and maximum temperatures within predetermined thresholds. 
     
     
         7 . A method according to  claim 2  further comprising the step of controlling the beam intensity is controlled such that the integrated circuit die is heated at a predetermined rate. 
     
     
         8 . A method according to  claim 2  further comprising the step of controlling the beam intensity such that the integrated circuit die temperature does not exceed a predetermined maximum. 
     
     
         9 . A method according to  claim 1  wherein the thermal release adhesive heats to the threshold temperature in less than 5 seconds. 
     
     
         10 . A method according to  claim 9  wherein the thermal release adhesive heats to the threshold temperature in less than 2 seconds. 
     
     
         11 . A method according to  claim 2  wherein the threshold temperature is less than 250° C. 
     
     
         12 . A method according to  claim 11  wherein the threshold temperature is between 170° C. to 190° C.